1. Field of the Invention
The present invention relates to an image forming apparatus of a copier, a printer, a facsimile or a composite machine thereof in full color applied with an electrophotography system. In particular, the present invention relates to an image forming apparatus capable of preventing a developer cartridge used in the image forming apparatus from being mistakenly installed or removed.
2. Description of the Related Art
In an image forming apparatus of this kind of a copier, a printer, a facsimile or a composite machine thereof or the like in full color applied with an electrophotography system, there is an image forming apparatus of so-called tandem type constituted such that a plurality of image forming portions in correspondence with respective colors of yellow, magenta, cyan, black and the like are arranged in parallel, and toner images of respective colors of yellow, magenta, cyan, black and the like formed at the respective image forming portions are directly transferred onto a record sheet, or secondarily transferred onto a record sheet via an intermediate transferring belt or similar means to thereby form an image in full color.
Further, in an image forming apparatus of a copier, a printer or the like in full color, mentioned above, there is an image forming apparatus of so-to-speak 4 cycle type constituted such that a plurality of developing units with respective colors of yellow, magenta, cyan, black and the like are arranged along the periphery of a developing unit main body contiguously to a single photosensitive drum, the developing units of the respective colors are moved to a developing position opposed to the photosensitive drum by rotating the developing unit main body, and rotating the photosensitive drum by a predetermined number of times to thereby form toner images of the respective colors of yellow, magenta, cyan, and black on the photosensitive drum, and the toner images of the respective colors of yellow, magenta, cyan, and black formed on the photosensitive drum are directly transferred onto a record sheet or secondarily transferred onto a record sheet via an intermediate transferring belt or similar means to thereby form an image in full color.
In the image forming apparatus of the tandem type and the 4 cycle type, the image forming apparatus of the 4 cycle type is characterized in being able to be downsized since only the single photosensitive drum is used.
There have already been proposed technologies with regard to the 4 cycle image forming apparatus disclosed in, for example, JP-A-2001-83765 and JP-A-2001-83766.
A color image recording apparatus according to JP-A-2001-83765, mentioned above, includes a rotating member arranged to assemble with a plurality of developing units including toner containing portions and developing rollers substantially in a circular ring shape in a state of disposing the developing rollers always on an outer peripheral side and rotating to move the developing units to an image forming position, and a photosensitive member containing unit integrally including a photosensitive member, a charging roller for charging the photosensitive member, and a cleaner portion for cleaning to recover a toner remaining on the photosensitive member for transferring an image developed on the photosensitive member by the developing roller to a record sheet via an intermediate transferring member. Whereas the developing unit is inserted into the apparatus from a lid portion of an upper face of the apparatus in the vicinity of the developing roller on the upper side of the rotating member from a direction orthogonal to an axis of the rotating member, the photosensitive member containing unit is inserted into the apparatus from an opening and closing position on a front side of the apparatus and guided to the image forming apparatus from a direction orthogonal to the developing roller, and constituted to carry out two kinds of rotation controls for rotating the rotating member by 90° at respective steps of forming images of the respective colors and rotating the rotating member to dispose the developing unit at the interchanging position when there is not the toner of any of the developing units.
Further, a color image recording apparatus according to JP-A-2001-83766, mentioned above, is a color image recording apparatus including a rotating member arranged to assemble a plurality of developing units having toner containing portions and developing rollers substantially in a circular ring shape in a state of disposing the developing rollers always on an outer peripheral side and rotating to move the developing units successively to an image forming position, and a photosensitive member containing unit constituted by integrally including a photosensitive member, a charging roller for charging the photosensitive member, a cleaner portion for cleaning to recover toner remaining on the photosensitive member for transferring an image developed on the photosensitive member by the developing rollers to a record sheet via an intermediate transferring member. Whereas the developing unit is inserted into the apparatus from a lid portion at an upper face of the apparatus to be mounted to the rotating member from a direction orthogonal to an axis of the rotating member, the photosensitive member containing unit is constituted to be inserted into the apparatus from an opening and closing portion on a front side of the apparatus to be guided to the image forming position from a direction orthogonal to the developing roller and constituted to be able to be able to simultaneously contain the toner remaining on the intermediate transferring member to the cleaner portion.
In the case of the color image recording apparatus according to JP-A-2001-83765 and JP-A-2001-83766, mentioned above, as shown in FIG. 27, the apparatus are constituted such that when any of developing units 100 runs out of toner, a rotating member 101 arranged with the four developing units 100 is rotated to move the developing unit 100 in which the toner is not present is moved to an interchanging position and the developing unit 100 is interchanged by opening a lid portion 102 at an upper face of the apparatus.
Meanwhile, as shown in FIG. 27, the developing unit 100 which is not disposed at the interchanging position is disposed at a position opposed to a photosensitive member containing unit 103 and therefore, there poses a problem that there is a concern that in a state of taking out the photosensitive member containing unit 103, the developing unit 100 which is not disposed at the interchanging position is exposed to outside and is taken out erroneously.
In the case of the color image recording apparatus according to JP-A-2001-83765, mentioned above, as shown in FIG. 27, there is present an obstacle 104 for preventing the developing unit 100 which is not disposed at the interchanging position from being able to attach or detach.
However, although it is conceivable to arrange the photosensitive containing unit over an outer periphery of the rotating member arranged to assemble with the plurality of developing units when the color image recording apparatus is downsized, in the case of being constituted in this way, there poses a problem that there is not a space of arranging the obstacle for preventing the developing unit which is not disposed at the interchanging position from being attached or detached when the photosensitive containing unit is removed and the developing unit which is not disposed to the interchange position cannot be prevented from being erroneously attached or detached.